Mar. zo 19 23 
Rosette Disease of Wheat and Its Control 
789 
SPREAD OF THE DISEASE 
BY INFESTED SOIE 
This point has been proved by experiments which involved the trans¬ 
ferring of infested soil to small plots of disease-free soil located in Alham¬ 
bra, Ill., and at Madison, Wis., and by introducing infested soil into 
soil sterilized with a 1 to 49 solution of 40 per cent formaldehyde and 
water at Granite City, Ill. The latter experiment is discussed under 
the head of parasitic factors. 
In all cases the typical symptoms of the rosette disease developed in 
the plots located at the two points given and in the soil-disinfection 
experiment where undisinfected, infested soil was introduced. In every 
case healthy plants developed in the local and disinfected soil. 
The summer-fallow experiments discussed under soil factors other 
than parasitic show that the causal factor can persist in the soil for at 
least two years without apparent loss of its disease-producing powers. 
BY INFESTED SEED 
In 1920 seed was selected from plants which had practically recovered 
from the attack of the rosette disease. In the fall this seed was sown in 
. field plots located at Madison, Wis., and Alhambra, Ill., and also in 
disinfected soil at Granite City, Ill. While the resulting plants were 
not robust, due to the poor quality of the seed used, all plots and soil 
containers were free from any indications of the rosette disease. Adja¬ 
cent plots receiving the infested soil in each case developed the disease. 
While these results demonstrate that the disease was not borne by 
the seed used in the experiment it is not felt that they are conclusive. 
Certain field observations lead to the belief that under certain conditions 
the disease is seed-borne. The foregoing results tend to indicate that 
the disease is not due primarily to a “running out” nor to constitutional 
weakness of the susceptible variety. 
BY INFESTED STUBBI/E 
Parallel experiments with the stubble of diseased plants were carried 
on with the seed and soil transmission experiments, and, as in the seed 
experiments, negative results were obtained. These results are not 
considered conclusive, however, and this point is being investigated 
further. 
CONTROL MEASURES 
Various control measures have been under investigation, and distinct 
progress has been made in controlling the disease through the use of 
resistant or immune varieties. 
As noted previously, various experiments on the applications of fer¬ 
tilizers, manure, and lime, and involving limited cropping methods, have 
failed to effect a control of the disease, although most of these have in¬ 
creased the percentage of recovery after the disease has developed. 
Seed treatments also have failed to effect a control. This is to be ex¬ 
pected, however, as the disease is soil-borne. The burning of stubble 
and the application of iron sulphate to the soil failed to give control. 
Extremely late seeding controls the disease to a considerable extent. 
However, the seeding must be late enough so that the plants do not 
emerge until the following spring, and for this reason the method is not 
practicable. 
